Quick answer
A flight data recorder (FDR) is a crash-protected unit that records aircraft parameters such as altitude, airspeed, heading, and control positions. Together with the cockpit voice recorder, it is commonly called the black box. Beyond accident investigation, operators download and read out FDR data to confirm that the system records every required parameter correctly.
What an FDR records
The FDR receives data from aircraft systems, typically through a data acquisition unit, and stores it in crash-protected memory. The cockpit voice recorder (CVR) is a separate function that records flight-crew audio, although some installations combine both.
Which parameters must be recorded depends on the aircraft and the operating rules. For turbine transport-category airplanes operated under part 121, 14 CFR 121.344 lists the required parameters, and Appendix M sets their range, accuracy, and resolution.
Which US rules apply
Recorder requirements depend on how the aircraft is operated and configured.
- 14 CFR 91.609: general flight data recorder and cockpit voice recorder equipage and operating rules
- 14 CFR 121.344: digital flight data recorder parameters for transport-category airplanes
- 14 CFR 135.152: flight data recorder requirements for aircraft in commuter and on-demand operations, by seating configuration
Why FDR data is downloaded and read out
A recorder can fail silently: a sensor or wiring fault may leave a parameter missing or wrong without any cockpit warning. Reading out a recording and checking each parameter is how operators find these dormant failures. Part 121 operators must also keep a correlation between recorded values and the corresponding measured values.
Check intervals come from the aircraft’s instructions for continued airworthiness and the operator’s maintenance program. FAA AC 20-141B expects those instructions to include check procedures and recommended intervals, and ICAO and some authorities call for periodic readouts. Follow the program that applies to your aircraft rather than a generic interval.
How a download and readout works
A technician connects ground equipment to the recorder, either installed on the aircraft or on the bench, and copies the recorded data. Equipment such as the KGB Aviation DART downloads data from many common recorders.
The data is then decoded into engineering units using the aircraft’s data frame, and parameters are reviewed for presence, range, and plausibility. The findings go back to maintenance so any recording faults can be corrected.
Frequently asked questions
What is the difference between an FDR and a CVR?
The flight data recorder stores aircraft parameters such as altitude, airspeed, and control positions. The cockpit voice recorder stores flight-crew audio and cockpit sounds.
How often does an FDR need a readout?
The interval comes from the aircraft’s instructions for continued airworthiness and the operator’s maintenance program. ICAO and some authorities call for periodic readouts, so confirm the requirement that applies to your operation.
Does MATS provide FDR download and readout?
Yes. MATS provides FDR download and readout support using its own KGB Aviation DART equipment, with applicability and service scope confirmed for each request.
Authoritative sources
This guide provides general procurement information and is not legal, customs, engineering, or airworthiness advice.
14 CFR 91.609: Flight data recorders and cockpit voice recorders 14 CFR 121.344: Digital flight data recorders for transport category airplanes FAA AC 20-141B: Airworthiness and Operational Approval of Digital Flight Data Recorder Systems SKYbrary: Flight Data Recorder (FDR)